PEDF peptide plus hyaluronic acid stimulates cartilage regeneration in osteoarthritis via STAT3-mediated chondrogenesis

Aims

Pigment epithelium-derived factor (PEDF) is known to induce several types of tissue regeneration by activating tissue-specific stem cells. Here, we investigated the therapeutic potential of PEDF 29-mer peptide in the damaged articular cartilage (AC) in rat osteoarthritis (OA).

Methods

Mesenchymal stem/stromal cells (MSCs) were isolated from rat bone marrow (BM) and used to evaluate the impact of 29-mer on chondrogenic differentiation of BM-MSCs in culture. Knee OA was induced in rats by a single intra-articular injection of monosodium iodoacetate (MIA) in the right knees (set to day 0). The 29-mer dissolved in 5% hyaluronic acid (HA) was intra-articularly injected into right knees at day 8 and 12 after MIA injection. Subsequently, the therapeutic effect of the 29-mer/HA on OA was evaluated by the Osteoarthritis Research Society International (OARSI) histopathological scoring system and changes in hind paw weight distribution, respectively. The regeneration of chondrocytes in damaged AC was detected by dual-immunostaining of 5-bromo-2'-deoxyuridine (BrdU) and chondrogenic markers.

Results

The 29-mer promoted expansion and chondrogenic differentiation of BM-MSCs cultured in different defined media. MIA injection caused chondrocyte death throughout the AC, with cartilage degeneration thereafter. The 29-mer/HA treatment induced extensive chondrocyte regeneration in the damaged AC and suppressed MIA-induced synovitis, accompanied by the recovery of cartilage matrix. Pharmacological inhibitors of PEDF receptor (PEDFR) and signal transducer and activator of transcription 3 (STAT3) signalling substantially blocked the chondrogenic promoting activity of 29-mer on the cultured BM-MSCs and injured AC.

Conclusion

The 29-mer/HA formulation effectively induces chondrocyte regeneration and formation of cartilage matrix in the damaged AC.

Fracture Characteristics of Commercial PEEK Dental Crowns: Combining the Effects of Aging Time and TiO2 Content

Polyetheretherketone (PEEK) is an emerging thermoplastic polymer with good mechanical properties and an elastic modulus similar to that of alveolar bone. PEEK dental prostheses for computer-aided design/computer-aided manufacturing (CAD/CAM) systems on the market often have additives of titanium dioxide (TiO₂) to strengthen their mechanical properties. However, the effects of combining aging, simulating a long-term intraoral environment, and TiO₂ content on the fracture characteristics of PEEK dental prostheses have rarely been investigated. In this study, two types of commercially available PEEK blocks, containing 20% and 30% TiO₂, were used to fabricate dental crowns by CAD/CAM systems and were aged for 5 and 10 h based on the ISO 13356 specifications. The compressive fracture load values of PEEK dental crowns were measured using a universal test machine. The morphology and crystallinity of the fracture surface were analyzed by scanning electron microscopy and an X-ray diffractometer, respectively. Statistical analysis was performed using the paired t-test (α = 0.05). Results showed no significant difference in the fracture load value of the test PEEK crowns with 20% and 30% TiO₂ after 5 or 10 h of aging treatment; all test PEEK crowns have satisfactory fracture properties for clinical applications. Fracture surface analysis revealed that all test crowns fractured from the lingual side of the occlusal surface, with the fracture extending along the lingual sulcus to the lingual edge, showing a feather shape at the middle part of the fracture extension path and a coral shape at the end of the fracture. Crystalline analysis showed that PEEK crowns, regardless of aging time and TiO₂ content, remained predominantly PEEK matrix and rutile phase TiO₂. We would conclude that adding 20% or 30% TiO₂ to PEEK crowns may have been sufficient to improve the fracture properties of PEEK crowns after 5 or 10 h of aging. Aging times below 10 h may still be safe for reducing the fracture properties of TiO₂-containing PEEK crowns.

Outcomes after arthroscopic treatment for scaphoid nonunion using ipsilateral radius bone graft and a headless compression screw: a comparison between the patients with and without avascular necrosis

PURPOSE

To determine whether avascular necrosis can affect clinical outcomes or the union incidence after arthroscopic bone grafting for the treatment of scaphoid nonunion.

METHODS

This retrospective comparative study included thirty-four patients with scaphoid nonunion that underwent arthroscopic bone graft from the ipsilateral radius and internal fixation. The patients were divided into two cohorts (group A, with avascular necrosis, n = 15; group B, without avascular necrosis, n = 19) based on pre-operative magnetic resonance imaging findings. Additionally, the patients were grouped in accordance with the location of nonunion (waist, n = 27; proximal pole, n = 7). The mean follow-up was 20.7 months (range 12.0-40.0 months). Clinical outcomes, including the visual analog scale (VAS) pain score, grip strength, range of motion (ROM), Mayo Wrist Score (MWS), and Disabilities of the Arm, Shoulder, and Hand (DASH) score, were evaluated. Radiographic measurements for carpal bone alignment were assessed as well.

RESULTS

Union rates did not differ between groups (group A, 93.3%; group B, 94.7%: p = 0.863), and the post-operative VAS pain score, ROM, and MWS were similar at follow-up for a minimum of one year. DASH and grip strength were significantly better in group B, but the intergroup differences were minimal (mean DASH 11.9 versus 9.6; mean grip strength 77.5% versus 95.4% of contralateral side). There was no significant intergroup difference in mean time to achieving union (group A, 14.9 weeks; group B, 14.6 weeks; p = 0.900). In post-operative radiographic assessments, no significant intergroup differences were noted in any of the parameters. Subgroup analysis regarding the location of nonunion showed there were no significant intergroup differences in union rates, mean time to achieving union, and clinical outcome measures at the last post-operative follow-up.

CONCLUSIONS

Arthroscopic bone grafting and internal fixation in the treatment of scaphoid nonunion provided good union rates and satisfactory outcomes regardless of vascularity status.

[Evaluation of thermal environment and human thermal comfort in 8 types of public places from 2019 to 2021]

Objective: To evaluate the thermal environment of different types of public places and the thermal comfort of employees, so as to provide scientific basis for the establishment of microclimate standards and health supervision requirements. Methods: From June 2019 to December 2021, 50 public places (178 times) of 8 categories in Wuxi were selected, including hotels, swimming pools (gymnasiums), bathing places, shopping malls (supermarkets), barber shops, beauty shops, waiting rooms (bus station) and gyms. In summer and winter, microclimate indicators such as temperature and wind speed were measured in all kinds of places, combined with the work attire and physical activity of employees in the places. Fanger thermal comfort equation and center for the built environment (CBE) thermal comfort calculation tool were used to evaluate the predicted mean vote (PMV), predicted percent dissatisfied (PPD) and standard effective temperature (SET) according to the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) 55-2020. The modification effects of seasonal and temperature control conditions on thermal comfort were analyzed. The consistency of GB 37488-2019 "Hygienic Indicators and Limits in Public Places" and ASHRAE 55-2020 evaluation results on thermal environment was compared. Results: The thermal sensation of hotel, barber shop staff and the gym front-desk staff were moderate, while the thermal sensation of swimming place lifeguard, bathing place cleaning staff and gym trainer were slightly warm in summer and winter. Waiting room (bus station) cleaning and working staff, shopping mall staff felt slightly warm in summer and moderate in winter. Service staff in bathing places felt slightly warm in winter, while staff in beauty salons felt slightly cool in winter. The thermal comfort compliance of hotel cleaning staff and shopping mall staff in summer was lower than that in winter (χ(2)=7.01, 7.22, P=0.008, 0.007). The thermal comfort compliance of shopping mall staff in the condition of air conditioning off was higher than that in the condition of air conditioning on (χ(2)=7.01, P=0.008). The SET values of front-desk staff in hotels with different health supervision levels were significantly different (F=3.30, P=0.024). The PPD value and SET value of the front-desk staff, and the PPD value of cleaning staff of hotels above three stars were lower than those of hotels below three stars (P<0.05). The thermal comfort compliance of front-desk staff and cleaning staff in hotels above three stars was higher than that in hotels below three stars (χ(2)=8.33, 8.09, P=0.016, 0.018). The consistency of the two criteria was highest among waiting room (bus station) staff (100.0%, 1/1) and lowest among gym front-desk staff (0%, 0/2) and waiting room (bus station) cleaning staff (0%, 0/1) . Conclusion: There are different degrees of thermal discomfort in different seasons, under the condition of air conditioning and health supervision, and the microclimate indicators can not fully reflect the thermal comfort of human body. The health supervision of microclimate should be strengthened, the applicability of health standard limit value should be evaluated in many aspects, and the thermal comfort of occupational group should be improved.

Biomechanical characteristics of self-expanding sinus stents during crimping and deployment_A comparison between different biomaterials

Self-expanding sinus stents are often used in functional endoscopic sinus surgery to treat inflamed sinuses. The PROPEL self-expanding sinus stent offers mechanical support to the sinus cavity to prevent restenosis. The stent is made of a bioabsorbable material (PLGA) that disappears after wound healing. However, complications such as foreign body sensation and severe stent migration/expulsion have been reported after implantation. Little is known about the contact characteristics of self-expanding sinus stents from when the stent is crimped into the insertion device through to deployment into the sinus cavity. This current study developed a test platform to analyze the biomechanical behavior of the stent during this process. Three common bioabsorbable materials, PLGA, PCL and Mg alloy, were evaluated to understand how the choice of material affects the biomechanical characteristics of self-expanding sinus stents. The results showed that the material can have a considerable influence on the contact characteristics during crimping and deployment. When crimped, the PLGA and Mg alloy stents showed much higher plastic strain and contact stress than the PCL stent. When deployed, the PCL stent had the largest contact area (4.3 mm²) and the lowest contact pressure (0.1 MPa) on the inner surface of the sinus canal. The results indicate that PCL could be a suitable choice for self-expanding sinus stents. This current study provides a method for observing the biomechanical characteristics of sinus stents during stent crimping and deployment.

Effect of cutting flute design features on primary stability of immediate implant placement and restoration: a dynamic experimental analysis

Self-tapping implants with self-cutting flutes may influence primary stability, especially for the immediate implant placement and restoration protocol in which implants are affixed to the bone in the apical portion. Screw geometry differs between brands, and the effect of apical design on its clinical outcomes remains unclear. This study is aimed at investigating the influence of cutting flute shape (spiral, straight, and without flute) on primary stability by using a dynamic experimental test. Six types of dental implants were designed using computer-aided design and computer-aided manufacturing technology, consisting of three types of cutting flute shapes along with two types of screw features. A dynamic mechanical test was performed using a cyclic loading scheme. The mechanical behaviors of resistance to lateral load (RLL), maximum force, and energy dissipation were compared between groups. In the dynamic test, implants without cutting flute also exhibited higher values in RLL, maximum force, and energy dissipation. The aggressive thread implant with straight flute displayed higher RLL and had a significantly higher values in RLL (p = 0.033) at the threshold point of bone-implant interface breakdown. The implants without cutting flutes exhibited higher primary stability. Straight flute design would improve RLL for aggressive thread implant.

Catastrophic failure of a titanium locking plate in a proximal humeral fracture: case report and literature review

Background

Angular stable locking plates have shown good clinical results in treating proximal humeral fractures, but complications are not uncommon. This study reported a rare case of catastrophic failure of a titanium locking plate. A retrieval analysis of the implants was performed using an optic microscope and a scanning electron microscope.

Case presentation

A 69-year-old male reported a right proximal humeral fracture at the surgical neck and was treated by open reduction and internal fixation with a locking plate system. Ninety-six days after surgery, the patient came to clinic for acute local pain over the shoulder without any trauma. The radiographs showed a complete breakage of the implant accompanying displaced fracture. Revision surgery was performed to restabilize the fracture with a longer locking plate. The follow-up radiographs at 9 months showed complete union of the bone fracture.

Conclusions

From the retrieval analysis, repetitive torsion loads on the vulnerable area of the implant are assumed to cause this catastrophic event. It is recommended that adequate activity restriction, such as reaching, be undertaken to avoid this rare complication. Current study also provides contributive information for the modification of plate design and pre-operative planning for device configuration to improve the success rate of locking plate fixation.

Influence of Aging on the Fracture Characteristics of Polyetheretherketone Dental Crowns: A Preliminary Study

Although polyetheretherketone (PEEK) is becoming more widely used in dentistry applications, little is known about how aging will affect this material. Therefore, this study aimed to investigate the influence of an aging treatment on fracture characteristics of PEEK dental crowns. Additionally, the impact of the addition of titanium dioxide (TiO₂) into PEEK was examined. Two types of commercial PEEK discs were used in this study, including TiO₂-free and 20% TiO₂-containing PEEK. The PEEK dental crowns were fabricated and aging-treated at 134 °C and 0.2 MPa for 5 h in accordance with the ISO 13356 specification before being cemented on artificial tooth abutments. The fracture loads of all crown samples were measured under compression tests. Results demonstrated that adding TiO₂ enhanced the fracture load of PEEK crowns compared to TiO₂-free PEEK crowns before the aging treatment. However, the aging treatment decreased the fracture load of TiO₂-containing PEEK crowns while increasing the fracture load of TiO₂-free PEEK crowns. The fracture morphology of TiO₂-containing PEEK crowns revealed finer feather shapes than that of the TiO₂-free PEEK crowns. We concluded that adding TiO₂ increased the fracture load of PEEK crowns without aging treatment. Still, the aging treatment influenced the fracture load and microscopic fracture morphology of PEEK crowns, depending on the addition of TiO₂.

The potential role of herbal extract Wedelolactone for treating particle-induced osteolysis: an in vivo study

Background

Osteolysis is one of the most prevalent clinical complications affecting people who undergo total joint replacement (TJR). Wedelolactone (WDL) is a coumestan compound derived from the Wedelia chinensis plant and has been demonstrated to exhibit anti-inflammatory properties. This study aimed to investigate the oral administration of WDL as a potential treatment for particle-induced osteolysis using a well-established mice calvarial disease model.

Methods

Thirty-two C57BL/6 J mice were randomized into four groups: Sham, vehicle, osteolysis group with oral WDL treatment for 4 weeks (WDL 4w), and osteolysis group treated for 8 weeks (WDL 8w). Micro-CT was used to quantitatively analyze the bone mineral density (BMD), bone volume/tissue volume (BV/TV) and trabecular bone thickness (Tb.Th). Osteoclast numbers were also measured from histological slides by two investigators who were blind to the treatment used.

Results

The results from micro-CT observation showed that BMD in the WDL 8w group improved significantly over the vehicle group (p < 0.05), but there was no significant difference between WDL 4w and 8w for BV/TV and Tb.Th. Osteoclast numbers in the WDL 4w group were also lower than the vehicle group (p < 0.05), but the difference between WDL 8w and 4w groups was not significant.

Conclusions

Particle-induced osteolysis is an inevitable long-term complication after TJR. The results of this animal study indicate that an oral administration of WDL can help reduce the severity of osteolysis without adverse effects.

Evaluation of graphene-derived bone scaffold exposure to the calvarial bone_in-vitro and in-vivo studies

Graphene is a novel material which has recently been gaining great interest in the biomedical fields. Our previous study observed that graphene-derived particles help induce bone formation in a murine calvarial model. Here, we further developed a blended graphene-contained polycaprolactone (PCL/G) filament for application in a 3D-printed bone scaffold. Since implants are expected to be for long-term usage, in vitro cell culture and in vivo scaffold implants were evaluated in a critical-size bone defect calvarial model for over 60 weeks. Graphene greatly improved the mechanical strength by 30.2% compared to pure PCL. The fabricated PCL/G scaffolds also showed fine cell viability. In animal model, an abnormal electroencephalogram power spectrum and early signs of aging, such as hair graying and hair loss, were found in the group with a PCL/G scaffold compared to pure PCL scaffold. Neither of the abnormal symptoms caused death of all animals in both groups. The long-term use of graphene-derived biomaterials for in-vivo implants seems to be safe. But the comprehensive biosafety still needs further evaluation.

[Efficacy of a recombinant bovine basic fibroblast growth factor gel for the treatment of moderate dry eye: a multicenter randomized double-blind parallel controlled clinical trial]

Objective: To compare the clinical efficacy of a recombinant bovine basic fibroblast growth factor (rb-bFGF) gel and a gel matrix in the treatment of moderate dry eye. Methods: It was a prospective random double-blind controlled study. One hundred patients diagnosed as moderate dry eye in Eye Institute and Affiliated Xiamen Eye Center of Xiamen University, Union Hospital Affiliated to Tongji Medical College of Huazhong University of Science and Technology, Beijing Tongren Hospital, Capital Medical University, Eye & ENT Hospital of Fudan University and Zhongshan Ophthalmic Center from August 2015 to April 2019 were divided into two groups: experimental group and control group. Two groups of patients were allocated to receive either a rb-bFGF gel or a gel matrix 4 times per day for 4 weeks. Subjective symptoms, break-up time of the tear film (BUT), Schirmer Ⅰ test (SⅠt) and corneal fluorescein sodium staining were assessed at baseline, 2 and 4 weeks after treatment. Bulbar impression cytology was evaluated at baseline and 4 weeks after treatment. Irritation of the rb-bFGF gel and the gel matrix was estimated after treatment. T test, Wilcoxon signed-rank test or Mann-Whitney U test was used for quantitative data, and Chi-square test was used for enumerative data. Results: Eighty-four subjects were included for statistical analyses after the exclusion of 16 subjects who were lost for followup, with an age of 43±14 years. There were 42 cases in the experimental group and the control group, respectively. There was no statistically significant difference between the two groups in demographic baseline characteristics before treatment (P>0.05). The total score of subjective symptoms was 7.17±3.60 and 5.95±3.25 at 2 and 4 weeks after therapy in the experimental group, which were lower than 9.48±3.88 before treatment (t=6.226, 6.563; both P<0.05); in the control group, it was 7.01±3.25 and 6.32±3.85 at 2 and 4 weeks after treatment, with a significant reduction in comparison with that before treatment (9.15±3.58; t=4.693, 4.726; both P<0.05). The median (lower quartile, upper quartile) BUT was 4.00 (2.40, 5.00) s and 4.64 (3.00, 5.00) s at 2 and 4 weeks after therapy in the experimental group, which were longer than 3.72 (2.00, 4.39) s before treatment (Z=-2.485, -3.152; both P<0.05). The BUT was 4.41 (2.79, 5.12) s at 2 weeks after therapy in the control group, which was of no statistical difference compared with 3.89 (2.09, 4.25) s before treatment (Z=-1.953, P>0.05). The BUT was 5.21 (3.00, 5.02) s at 4 weeks after therapy in the control group, which was longer than that before treatment (Z=-2.485, P<0.05). The SⅠt score was 7.31 (3.75, 10.00) mm and 8.50 (4.00, 11.00) mm at 2 and 4 weeks after therapy in the experimental group, which were significantly higher than 6.69 (2.00, 8.13) mm before treatment (Z=-2.031, -2.236; both P<0.05); in the control group, it was 6.82 (2.00, 8.25) mm and 6.86 (3.00, 9.25) mm at 2 and 4 weeks after therapy, which were not significantly increased compared with 6.50 (2.00, 7.75) mm before treatment (Z=-0.179, -1.161; both P>0.05). The corneal fluorescein sodium staining points were 5.00 (2.00, 5.00) and 3.71 (0.00, 5.00) at 2 and 4 weeks after therapy in the experimental group, which were significantly lower than 7.10 (5.00, 7.00) before treatment (t=-2.895, -4.639; both P<0.05); those in the control group were 5.52 (0.00, 7.00) and 6.19 (0.75, 6.25) at 2 and 4 weeks after treatment, with a significant reduction in comparison with 8.90 (5.00, 10.50) before treatment (t=-2.776, -1.991; both P<0.05). The differences in the average total score of subjective symptoms, BUT, SIt, and corneal fluorescein sodium staining points between both groups were not statistically significant at each time point. The impression cytology grade was decreased from 1.72 (1.00, 2.00) before treatment to 0.94 (0.00, 2.00) at 4 weeks after therapy in the experimental group (Z=-2.803, P<0.05). The staining grade of conjunctival imprinted cells in the control group was 1.42 (1.00, 2.00) at 4 weeks, which showed no statistical significance compared with 1.56 (1.00, 2.00) before treatment (Z=1.195, P>0.05). The impression cytology grade was significantly reduced in the experimental group compared with the control group at 4 weeks after treatment (Z=-3.308, P<0.05). The number of goblet cells was 10.90 (5.00, 20.00) at 4 weeks after therapy in the experimental group, which was significantly higher than 6.30 (5.00, 8.00) before treatment (Z=-2.383, P<0.05); in the control group, it was 8.36 (4.00, 12.00) at 4 weeks after treatment, with no significant increase in comparison with that before treatment [7.55 (5.00, 11.00)] (Z=-0.095, P>0.05). The number of goblet cells was not significantly increased in the experimental group compared with the control group at 4 weeks after treatment (Z=-1.162, P>0.05). Most patients indicated that the drug was non-irritating, and no patient had intolerable irritation affecting daily lives at 4 weeks after therapy; there was no difference between the two groups (Z=-0.290, P>0.05). Conclusions: Both the rb-bFGF gel and the gel matrix can effectively improve the symptoms and signs of moderate dry eye. However, compared with the gel matrix, the rb-bFGF gel shows obvious advantages in promoting conjunctival epithelial cell repair and increasing the number of goblet cells. (Chin J Ophthalmol, 2021, 57: 930-938).

Influences of screw design features on initial stability in immediate implant placement and restoration

BACKGROUND

Self-tapping screws have been extensively used for dental implants. Their biomechanical behavior is highly associated with their clinical success, particularly for screws used for immediate implant placement and restoration, because occlusal forces can directly affect the loading transfer at the bone-implant interface after implantation. The effect of implant design on the initial stability of self-tapping screws remains unclear. This study explored the biomechanical behaviors of implant stability in standardized implants with different design features.

METHODS

Six types of dental implants were designed using computer-aided design/computer-aided manufacturing technology, including three types of cutting flute shapes (spiral, straight, and non-self-tapping) combined with two types of screw features. Peak insertion torque values were first recorded; initial stability levels were subsequently evaluated in terms of the maximum force and resistance to lateral loads using an electrodynamic test system.

FINDINGS

The peak insertion torque values, maximum force, and resistance to lateral loads of the non-self-tapping groups were higher than those of the self-tapping groups by 17%-90% (p < 0.01). The peak insertion torque values of the Straumann implant with a spiral flute was higher than that of the original straight flute by 20% (p < 0.001). However, compared with the original spiral flute, the Nobel Biocare implant with straight flute had a 23% higher maximum force (p = 0.016) and 24.5% higher resistance (p = 0.012) under lateral loading.

INTERPRETATION

Changing the flute design would affect initial implant stability. Non-self-tapping implants exhibited superior initial stability than did self-tapping implants.

[A multicenter, randomized, double-masked, placebo-controlled trial of compound wild chrysanthemum eye masks for mild and moderate dry eye]

Objective: To investigate the clinical efficacy and safety of compound wild chrysanthemum eye masks for mild and moderate dry eye. Methods: In this double-masked, multicenter, placebo-controlled, randomized trial, middle-aged and elderly patients with mild and moderate dry eye were enrolled from six hospitals (Xiamen Eye Center of Xiamen University, China-Japan Friendship Hospital, Peking Union Medical College Hospital, Wangjing Hospital of China Academy of Chinese Medical Sciences, Affiliated Eye Hospital of Shandong University of Traditional Chinese Medicine and Hebei Eye Hospital). The patients were assigned to the compound wild chrysanthemum eye mask group and the eye mask simulator group based on the random number table. Subjective symptoms of dry eye, visual acuity, break-up time (BUT), Schirmer Ⅰ test, and corneal fluorescent staining were evaluated in all patients before treatment and at 1 and 2 weeks after treatment. All adverse reactions during the treatment and follow-up were recorded. Results: A total of 120 patients were enrolled. Among them, 112 subjects were included for statistical analyses after the exclusion of 8 subjects who were lost for follow-up or had an adverse event, with an age of (54.26±7.44) years. All the indicators were equally comparable between the two groups. Before treatment and at 1 and 2 weeks after treatment, the median (lower quartile, upper quartile) of total score of questionnaires in the eye mask group was 14.50 (10.00, 19.00), 9.00 (5.00, 14.00) and 7.00 (4.00, 10.00), respectively, and that in the control group was 14.00 (9.00, 22.50), 12.00 (6.00, 20.00) and 10.00 (3.50, 17.00), respectively. The score decreased significantly in both groups after 1 week (t=9.1604, S=398.00; P<0.01) and 2 weeks (S=681.00, 575.50; P<0.05) of treatment. The total score of questionnaires in the eye mask group was significantly lower than that in the control group (Z=3.27, 2.81; P<0.05) after treatment. After 1 week of treatment, the average BUT of the eye mask group was (5.71±2.31) s, which was significantly longer than that before treatment (5.06±2.00) s (S =208.50, P<0.05). But there was no significant difference in the control group (S=150.00, P>0.05). After 2 weeks of treatment, there was statistically significant difference in BUT between the two groups (S=407.00, t=3.07; P<0.01). After 1 week of the treatment, the amount of tear secretion in the eye mask group [(6.88±4.78) mm] was significantly larger than that before treatment (S=196.50, P<0.05), while the control group [(6.80±5.85) mm] showed no significant difference (S=55.00, P<0.05). After 2 weeks of the treatment, the amount increased significantly to (7.43±4.86) mm and (7.29±4.56) mm, respectively, in both groups (t=-3.29, -2.26; P<0.05). The difference in the average BUT, Schirmer Ⅰ test result and corneal fluorescent staining between both groups was not statistically significant at each time point. Five mild adverse events occurred, including 2 adverse events (2 times, 3.51%) in the eye mask group and 3 adverse events (4 times, 5.36%) in the control group. Conclusions: Compound wild chrysanthemum eye masks can effectively improve the symptoms and physical signs of mild and moderate dry eye and can be used as an auxiliary treatment. (Chin J Ophthalmol, 2021, 57: 601-607).

Influence of Antibiotic-Loaded Acrylic Bone Cement Composition on Drug Release Behavior and Mechanism

Periprosthetic joint infection (PJI) is a devastating complication after total joint replacement with considerable morbidity and large economic burdens. Antibiotic-Loaded Bone Cement (ALBC) has been developed as a valuable tool for local administration and is becoming one of the most effective methods for the prevention and treatment of orthopedic infections. Controlling antibiotic release from ALBC is critical to achieve effective infection control, however, the antibiotic elution rates are generally low, and the mechanisms are poorly understood. Thus, the present study aims to investigate the effects of the basic acrylic bone cement components, including liquid/powder (monomer-to-polymer) ratios, radiopacifier, initiator, and doses of antibiotics on the porosity, antibiotic elution rates and mechanical properties of polymethylmethacrylate (PMMA) based ALBC. The obtained results from the in vitro studies suggested that a reduction in the liquid/powder ratio and an increase in the radiopacifier ratio and gentamicin doses led to increased porosity and release of antibiotic, while the initiator ratio exerted no effect on elution rates. In conclusion, we hope that by varying the composition of ALBC, we could considerably enhance the antibiotic elution rates by increasing porosity, while maintaining an adequate mechanical strength of the bone cements. This finding might provide insights into controlling antibiotic release from ALBC to achieve effective infection control after total joint replacement surgery.

Dietary Patterns and Muscle Mass, Muscle Strength, and Physical Performance in the Elderly: A 3-Year Cohort Study

OBJECTIVES

Nutritional support effectively prevents and treats sarcopenia; however, the influence of overall dietary patterns on sarcopenia parameters is less investigated. This study aimed to determine the association between adherence to Mediterranean-style diet (MD), Dietary Approaches to Stop Hypertension (DASH), Japanese Food Guide Spinning Top (JFG-ST), and modified JFG-ST (mJFG-ST) and muscle mass, muscle strength, and physical performance in community-dwelling Japanese elderly.

DESIGN AND SETTINGS

This prospective cohort study recruited individuals aged over 60 years from a community college in Nagoya, Japan.

PARTICIPANTS AND MEASUREMENTS

A total of 666 participants were followed up annually from 2014 to 2017. Demographic data, anthropometric measurements, and sarcopenia parameters including walking speed (WS), hand grip strength in the dominant hand (HGS), and skeletal mass index (SMI) were recorded. Self-recall dietary intake was assessed using a validated food frequency questionnaire comprising 29 food groups. Adherence to MD, DASH, JFG-ST, and mJFG-ST was determined by tertiles.

RESULTS

At baseline, the mean age of all participants (56.5% women) was 69.4±4.4 years. WS, HGS, and SMI were 1.4±0.2 (m/s), 28.9±8.1 (kg), and 6.7±1.0 (kg/m2), respectively. In longitudinal analysis, participants with higher JFG-ST adherence scores were more likely to have higher SMI (Q3 vs. Q1: mean difference, 0.048; p=0.04) after adjustment, and its benefits were more evident in men (Q2 vs. Q1: mean difference, 0.098; p=0.047; Q3 vs. Q1: mean difference, 0.091; p=0.017) than in women. WS and HGS were not associated with any type of dietary pattern.

CONCLUSIONS

Adherence to JFG-ST was positively associated with SMI in Japanese community-dwelling elderly adults aged over 60 years, specifically in men. The country-specific dietary recommendations are required to be developed for sarcopenia prevention.

Enhanced expression of coxsackievirus and adenovirus receptor in lipopolysaccharide-induced inflammatory macrophages is through TRIF-dependent innate immunity pathway

AIMS

Inflammatory macrophages have been proposed as a therapeutic target for joint disorders caused by inflammation. This study aimed to investigate the expression and regulation of coxsackievirus-adenovirus receptor (CAR) in lipopolysaccharide (LPS)-stimulated inflammatory macrophages whereby to evaluate the feasibility of virus-directed enzyme prodrug therapy (VDEPT).

MAIN METHODS

Macrophage cell lines (RAW264.7 and J774A.1) and primary macrophage cells derived from rat spleen were used to evaluate the expression of CAR protein or CAR mRNA. Specific inhibitors for TLR4 pathway were used to investigate the regulation of CAR expression. CAR expression in rat joints was documented by immunohistochemistry. Conditionally replicating adenovirus, CRAd-EGFP(PS1217L) or CRAd-NTR(PS1217H6), and non-replicating adenovirus CTL102 were used to transduce genes for enhanced green fluorescent protein (EGFP) or nitroreductase (NTR), respectively. The expression of EGFP, NTR, and the toxicity induced by CB1954 activation were evaluated.

KEY FINDINGS

The in vitro experiments revealed that CAR upregulation was mediated through the TLR4/TRIF/IRF3 pathway in LPS-stimulated inflammatory macrophage RAW264.7 and J774A.1 cells. The inflammatory RAW264.7 cells upregulated CAR expression following LPS stimulation, leading to higher infectability, increased NTR expression, and enhanced sensitization to CB1954. In animal experiments, the induction of CAR expression was observed in the CD68-expressing primary macrophages and in the CD68-expressing macrophages within joints following LPS stimulation.

SIGNIFICANCE

In conclusion, we report an enhanced CAR expression in inflammatory macrophages in vitro and in vivo through the immune response elicited by LPS. Thus, the TLR4/TRIF/IRF3 pathway of macrophages, when activated, could facilitate the therapeutic application of adenovirus-mediated VDEPT.

Effect of material selection on tibial post stresses in posterior-stabilized knee prosthesis

Aims

The material and design of knee components can have a considerable effect on the contact characteristics of the tibial post. This study aimed to analyze the stress distribution on the tibial post when using different grades of polyethylene for the tibial inserts. In addition, the contact properties of fixed-bearing and mobile-bearing inserts were evaluated.

Methods

Three different grades of polyethylene were compared in this study; conventional ultra high molecular weight polyethylene (UHMWPE), highly cross-linked polyethylene (HXLPE), and vitamin E-stabilized polyethylene (VEPE). In addition, tibial baseplates with a fixed-bearing and a mobile-bearing insert were evaluated to understand differences in the contact properties. The inserts were implanted in neutral alignment and with a 10° internal malrotation. The contact stress, von Mises stress, and equivalent plastic strain (PEEQ) on the tibial posts were extracted for comparison.

Results

The stress and strain on the tibial post for the three polyethylenes greatly increased when the insert was placed in malrotation, showing a 38% to 56% increase in von Mises stress and a 335% to 434% increase in PEEQ. The VEPE insert had the lowest PEEQ among the three materials. The mobile-bearing design exhibited a lower increase in stress and strain around the tibial posts than the fixed-bearing design.

Conclusion

Using VEPE for the tibial component potentially eliminates the risk of material permanent deformation. The mobile-bearing insert can help to avoid a dramatic increase in plastic strain around the tibial post in cases of malrotation. The mobility allows the pressure to be distributed on the tibial post and demonstrated lower stresses with all three polyethylenes simulated.

Cite this article: Bone Joint Res 2020;9(11):768–777.

Modifiable factors related to 7-year renal outcomes in subjects with type 2 diabetes and chronic kidney disease stage 3

Background and Aims

Subjects with diabetes are prone to a rapid decline in renal function and major adverse cardiovascular events when they reach chronic kidney disease (CKD) stage 3. This study aimed to identify modifiable risk factors associated with the progression of CKD in this population.

Settings and Design

An observational cohort study.

Methods and Materials

A total of 320 type 2 diabetic patients with CKD stage 3 registered in the shared-care-system in our hospital in 2010 were regularly followed up for 7 years. Demographic, laboratory, medication, and fundus examination data of these subjects were collected and analyzed.

Statistical Analysis Used

Cox regression was used to identify factors associated with changes in CKD stage.

Results

During the 7-year follow-up period, 204 cases (63.7%) remained at CKD stage 3 while 79 cases (24.7%) progressed to stage 4 or 5 and 37 cases (11.6%) improved to stage 1 or 2. The change in estimated glomerular filtration rate (eGFR) in the first 2 years and variations in glycated hemoglobin (HbA1c) over 7 years were independent factors of both progression (hazard ratio (HR) 1.098 and 1.710, respectively) and improvement (HR 0.919 and 0.231, respectively) of CKD stage. Variations in systolic blood pressure (SBP) was also found as an independent factor for progression of renal function (HR 1.052).

Conclusions

Our results demonstrated that fluctuations in HbA1c and SBP, and changes in eGFR during the first 2 years of treatment were associated with the long-term renal outcomes in type 2 diabetic patients with CKD stage 3.

Effect of implant design on the initial biomechanical stability of two self-tapping dental implants

BACKGROUND

This study evaluated the effect of two self-tapping implants on implant stability in immediate implantation.

METHODS

Two types of self-tapping implants, straight flute (STF) and spiral flute (SPF) designs, were studied. Two synthetic bone blocks with varying densities (0.32 g/cm³ and 0.16 g/cm³) were chosen to simulate the bone quality of the anterior maxilla. Insertion torque values were measured by a torque testing machine during implant insertion. Four biomechanical tests were performed: resonance frequency analysis was conducted using the Osstell device, and the strengths of screw push-in, lateral bending, and pull-out were evaluated using an MTS machine. The strength for each design feature was obtained by averaging the results of 10 trials. In total, 40 specimens were tested for each bone density. Statistical difference was determined by one-way analysis of variance followed by Bonferroni post hoc multiple tests between groups.

FINDINGS

The STF and SPF groups exhibited similar insertion torque values (p = 0.525 in low-density bone, and p = 0.99 in high-density bone). A significant difference (p < 0.001) was observed in the push-in test between the two groups when low-density bone was tested. The SPF group exhibited a significantly higher lateral bending force (p = 0.001) and a higher stiffness (p < 0.001) than the STF group in high-density bone. The SPF design attained higher (p < 0.001) ISQ numbers than the STF design, but all numbers were below 60.

INTERPRETATION

Implant stability can be influenced by the apical fixture design of self-tapping implants in immediate implantation.

In vitro and in vivo Biological Responses to Graphene and Graphene Oxide: A Murine Calvarial Animal Study

BACKGROUND

Graphene and its derivatives have recently gained popularity in the biomedical field. Previous studies have confirmed that both the mechanical strength and wear resistance of graphene-containing polyethylene have been greatly improved. Therefore, it is being considered as an alternative for artificial joint replacement liners. Based on the literature, the wear debris generated from the traditional polymers used for orthopedic liners could lead to particle-induced osteolysis and, consequently, failure of joint replacement. However, the biological response of this novel graphene-based polymer is still unclear. Therefore, the current study aimed to investigate the in vitro and in vivo biological effects of graphene and graphene oxide (GO) particles on bone.

MATERIALS AND METHODS

The biological responses of graphene and GO particles were tested via in vitro and murine calvarial in vivo models. In the in vitro model, murine macrophage cells were mixed with particles and hydrogel and printed into two differently designed scaffolds; the induced proinflammatory cytokines were then tested. In the murine in vivo model, the particle size distribution was measured via SEM, and these particles were then administrated in the calvarial area, referring to our established model. A micro-CT and histological analysis were performed to examine the biological effects of the particles on bone health. The data were analyzed via the one-way analysis of variance to determine the differences between the groups.

RESULTS

Both graphene and GO induced significantly higher TNF-α and IL-6 secretion compared with the control in the three-dimensional in vitro model. In the murine calvarial in vivo test, the graphene and GO particles increased the bone mass compared with the sham groups in the micro-CT analysis. Bone formation was also observed in the histological analysis.

CONCLUSION

In these in vivo and in vitro studies, the graphene and GO wear debris did not seem to induce harmful biological response effect to bone. Bone formation around the skull was observed in the calvarial model instead. Graphene-containing biomaterials could be a suitable new material for application in orthopedic prostheses due to their benefit of eliminating the risk of particle-induce osteolysis.

Combined Impact of Physical Frailty and Social Isolation on Rate of Falls in Older Adults

OBJECTIVES

The aim of this study was to examine the impact of the combination of physical frailty and social isolation on falling in community-dwelling older adults.

DESIGN

A cross-sectional study of data obtained at registration in a randomized control trial.

SETTING

Community-based study of participants recruited from Toyota, Japan.

PARTICIPANTS

380 community-dwelling older adults (47.9% women, mean age = 72.3 ± 4.6 years).

MEASUREMENTS

Participants were categorized as non-frail or pre-frail/frail based on the Fried frailty criteria (slowness, weakness, exhaustion, low activity, and weight loss). Social isolation was examined using the Lubben Social Network Scale (LSNS-6), and scores lower than 12 points indicated social isolation. Participants were divided into four groups depending on pre-frail/frail status and social isolation, and experiences of multiple falls over the past year were compared between the groups.

RESULTS

Participants were classified into robust (n = 193), physical frailty (PF; n = 108), social isolation (SI; n = 43), and PF with SI (PF+SI; n = 36) groups. A total of 38 (10.0%) participants reported multiple falls. Logistic regression analysis showed that PF and SI groups were not independently associated with falling (PF: OR 1.64, 95% CI 0.65-4.16, SI: OR 2.25, 95% CI 0.77-6.58), while PF+SI group was significantly associated with falling compared with the robust group (OR 3.06, 95% CI 1.00-9.34, p = 0.049) after controlling for confounding factors.

CONCLUSION

Our findings support the assertion that coexistence with physical frailty and social isolation were associated with falling in the older adults.

Abutment screw withdrawal after conical abutment settlement: A pilot study

OBJECTIVE

This study investigated the effects of abutment screw withdrawal after conical abutment settlement on the stability of the implant-abutment connection.

MATERIALS AND METHODS

Twenty implants of a conical connection system were used. Two two-piece abutment designs were used: cone only (n = 10; NI) and cone plus octagonal index design (n = 10; I); for each design, five samples were used with (S) and without (NS) abutment screw withdrawal before a cyclic test. Finally, four groups, namely Gr S(NI), Gr S(I), Gr NS(NI), and Gr NS(I), were included. The cyclic test included cyclic loading of 20-200 N, 30°, and 4-mm off-axis to implant axis at 10 Hz for 10⁶ cycles, simulating a clinical time interval of 40 months. The fatigue cycles were recorded. The axial displacement of the conical abutments during abutment settlement, screw withdrawal, and cyclic loading were measured. Abutment morphology was examined through scanning electron microscopy (SEM).

RESULTS

Only Gr NS(NI) failed the test, indicating that without the index design and abutment screw withdrawal, and connection stability seriously deteriorated. Gr NS(I) exhibited significantly higher axial displacement into the implant after abutment settlement than did Gr NS(NI). It also exhibited continuous axial displacement into the implant after cyclic loading. SEM after cyclic testing in Gr NS(I) revealed marked burnishing on lateral edges of the index, indicating that the index design provides an antitorsional ability.

CONCLUSION

Although this study has few limitations, abutment screw withdrawal is feasible in this conical implant-abutment connection system with index design.

[Gender difference in clinical manifestations and comorbidities in the patients with spondyloarthritis]

Objectives: The aim of the study was to determine whether there was gender difference in clinical manifestations and comorbidities in the patients with Spondyloarthritis (SpA) in China. Methods: 346 patients fulfilling ASAS criteria for SpA were recruited from the Third Affiliated Hospital of Sun Yat-sen University, including 280 males and 66 females. A comparison was conducted in terms of age at onset, disease course, family history, HLA-B27 positivity, clinical manifestations, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP), the bath ankylosing spondylitis disease activity index (BASDAI) and AS disease activity score (ASDAS), and comorbidities between male and female patients. Results: Compared with female patients, male patients were younger at disease onset (22±7 vs 27±9, P<0.001),had higher rates of morning stiffness (74.3%), and higher scores of CRP and ASDAS-CRP (P<0.010, P=0.014). However, no significant gender difference was observed in other clinical parameters like clinical manifestations, family history, HLA-B27 positivity, BASDAI, and BASFI and treatment. Male SpA patients had a higher prevalence of Hepatitis B virus (HBV) infection (26.2%) than that of female patients (8.3%), and a higher prevalence of osteoporosis (30.5% vs 14.3%,P<0.01), especially with a lower lumbar T score. Logistic regression analysis reviewed that limited weight (OR=0.94, P<0.001), high ASDAS-CRP (OR=1.58, P=0.006) and male (OR=8.02, P=0.004) are more inclined to have osteoporosis. Conclusion: Compared with female patients, male patients were younger at disease onset and higher scores of CRP and ASDAS-CRP. No significant gender difference was observed in clinical manifestations, family history, HLA-B27 positivity, BASDAI, and BASFI and treatment. Male SpA patients had a higher prevalence of HBV infection and osteoporosis than female patients. Comorbidities should be paid more attention in the patients with SpA.

PEDF-derived peptide promotes tendon regeneration through its mitogenic effect on tendon stem/progenitor cells

Background

Tendon stem/progenitor cells (TSPC) exhibit a low proliferative response to heal tendon injury, leading to limited regeneration outcomes. Exogenous growth factors that activate TSPC proliferation have emerged as a promising approach for treatment. Here, we evaluated the pigment epithelial-derived factor (PEDF)-derived short peptide (PSP; 29-mer) for treating acute tendon injury and to determine the timing and anatomical features of CD146- and necleostemin-positive TSPC in the tendon healing process.

Methods

Tendon cells were isolated from rabbit Achilles tendons, stimulated by the 29-mer and analyzed for colony-forming capacity. The expression of the TSPC markers CD146, Oct4, and nestin, induced by the 29-mer, was examined by immunostaining and western blotting. Tendo-Achilles injury was induced in rats by full-thickness insertion of an 18-G needle and immediately treated topically with an alginate gel, loaded with 29-mer. The distribution of TSPC in the injured tendon and their proliferation were monitored using immunohistochemistry with antibodies to CD146 and nucleostemin and by BrdU labeling.

Results

TSPC markers were enriched among the primary tendon cells when stimulated by the 29-mer. The 29-mer also induced the clonogenicity of CD146⁺ TSPC, implying TSPC stemness was retained during TSPC expansion in culture. Correspondingly, the expanded TSPC differentiated readily into tenocyte-like cells after removal of the 29-mer from culture. 29-mer/alginate gel treatment caused extensive expansion of CD146⁺ TSPC in their niche on postoperative day 2, followed by infiltration of CD146⁺/BrdU⁻ TSPC into the injured tendon on day 7. The nucleostemin⁺ TSPC were located predominantly in the healing region of the injured tendon in the later phase (day 7) and exhibited proliferative capacity. By 3 weeks, 29-mer-treated tendons showed more organized collagen fiber regeneration and higher tensile strength than control tendons. In culture, the mitogenic effect of the 29-mer was found to be mediated by the phosphorylation of ERK2 and STAT3 in nucleostemin⁺ TSPC.

Conclusions

The anatomical analysis of TSPC populations in the wound healing process supports the hypothesis that substantial expansion of resident TSPC by exogenous growth factor is beneficial for tendon healing. The study suggests that synthetic 29-mer peptide may be an innovative therapy for acute tendon rupture.

[Clinical effects of adjacent fasciocutaneous flaps in repairing small wounds with bone or steel plate exposure in anterior tibia]

Objective: To explore the clinical effects of adjacent fasciocutaneous flaps in repairing small wounds with bone or steel plate exposure in anterior tibia. Methods: Twelve patients with small wounds of bone or steel plate exposure in anterior tibia covering area of 2 cm×2 cm to 5 cm×3 cm were admitted to our unit from January 2014 to December 2016. A circular or elliptical adjacent fasciocutaneous flap was designed on the normal skin located at the inside or outside of the wound according to the size of wound after thorough debridement. The pedicle of the flap was located at the proximal end and transferred through the subcutaneous tunnel to cover the wound. The sizes of flaps were 3 cm×3 cm to 6 cm×4 cm. Flaps were fixed with interrupted sutures and drainage rubber sheets were placed under the flaps. The drainage rubber sheets were removed within 24 to 48 hours. The donor area was repaired by medium-thickness skin graft collected from homolateral outer thigh. Results: All the flaps of 9 patients survived. Two patients had necrosis at the distal end of the flaps and were cured by changing dressing. One patient had tension blisters on the flap and was cured by removing blisters and improving microcirculation. All patients were followed up for 3 months, and the flaps were good in blood supply, appearance, and color, with hypaesthesia. Conclusions: Repair of small wounds with bone or steel plate exposure in anterior tibia by adjacent fasciocutaneous flap is simple in surgical procedure and does not damage the well-known blood vessels, and the appearance, texture, and thickness of flaps are close to the skin of anterior tibia region. It is a good choice for repairing this kind of wounds and worth promoting in clinic.

Elastoplastic behavior of highly cross-linked and vitamin E-stabilized polyethylene - A biomechanical study

BACKGROUND

Vitamin E-stabilized cross-linked polyethylene has been touted to alleviate the negative effects of oxidation. Although it has demonstrated significant improvements in wear resistance, bio-tribology, and oxidative resistance, little is known about the effect of antioxidants and dosage of cross-linking on the mechanical strength. This study aimed to evaluate the mechanical properties of these novel materials, which are commonly used in orthopedic implants.

METHODS

Samples of different polymers were prepared with various levels of cross-linking and with or without vitamin E-stabilization and then tested according to ASTM D695 and D638. The elastoplastic characteristics under compression and tension were compared between the groups.

FINDINGS

Vitamin E-stabilized cross-linked polyethylene showed a significant increase in elastic modulus over other groups, with a maximum increase of 26% in compression and 40% in tension when compared to the highly cross-linked group without vitamin E stabilization. The elastoplastic behavior under compression differed to that in tension for all polymers, demonstrating the anisotropic characteristics of these polymers.

INTERPRETATION

The lower mechanical strength of highly cross-linked polyethylene has been a complication with the use of this polymer in orthopedic liners. This current study suggests that vitamin E-stabilized cross-linked polyethylene could be a suitable alternative material for knee implants because of its improved strength in resisting external forces.

[The transformation of microcystin-LR during tap water treatment process and analysis of its degradation products]

Objective: To establish a liquid chromatography-tandem mass spectrometry (LC/MS/MS) method for the determination of microcystin-LR (MC-LR) in drinking water, investigate its removal efficiency during tap water advanced treatment process and analyze its degradation products in the tap water. Methods: Two parallel water samples were collected from each point of tap water advanced treatment process in September 2015, November 2015 and January 2016, respectively, and treated by mixing, filtration, concentration, elution, nitrogen blow and re-dissolvement. The samples were analyzed by LC/MS/MS to determine the MC-LR concentration and its removal efficiency during treatment process. The combination of actual water enrichment (including source water enrichment of 50 times and 1 500 times concentrated, finished water enrichment of 50 times and 2 500 times concentrated) and laboratory simulated water (including the mixture of MC-LR and liquid chlorine in the mass ratio of 1∶10, 1∶20, 1∶100 and 1∶1 000, respectively) were used to qualitative analyze the MC-LR degradation products by Orbitrap mass spectrometry. Results: The linearity of MC-LR ranged from 2 to 200 μg/L with the detection limit of 0.007 9 μg/L and the limit of quantification of 0.026 3 μg/L. The recovery rate of MC-LR from different contration in drinking water were from 94.88%-101.47%. The intra-day precision was 2.51%-7.93% and the intra-day precision was 3.24%-8.41%. The average concentration of MC-LR in source water was (0.631±0.262) μg/L, 94.0% of which can be removed by ozone exposure while the concentrate was (0.038±0.016) μg/L, biological pre-treatment and chlorination. The remaining can hardly be removed by sand filtration, ozone exposure, activated carbon, ultrafiltration and other processes. The MC-LR average concentration in the finished water maintained at about (0.036±0.016) μg/L. Degradation products including hydroxy-microcystin, methyl-hydroxy-microcystin, methyl-microcystin were identified in the laboratory simulated water of the mixture of MC-LR and liquid chlorine in the mass ratio of 1∶10. Conclusion: The established MC-LR detection method can be well applied to the monitoring of MC-LR in drinking water due to its simple pre-treatment process and good methodological validation parameters. The degradation products of treatment processes was different.

Development, characterization and virus susceptibility of a continuous cell line from the caudal fin of marbled eel (Anguilla marmorata)

A continuous cell line consisting mostly of epithelioid cells was established from the caudal fin of marbled eels (Anguilla marmorata) and designated as marbled eel caudal fin (MECF)-1. The cells multiplied well in Leibovitz's L-15 medium containing 2% to 15% foetal bovine serum at temperatures of 20°C to 35°C and were subcultured for >90 passages during a 5-year period from 2012 to 2017. Transcripts of ictacalcin, keratin 13, cd146, nestin, ncam1 and myod1 were demonstrated in the cells using reverse transcription polymerase chain reaction. The results indicated that MECF-1 was composed of epidermal and mesenchyme stem and progenitor cells including myoblasts. MECF-1 was susceptible to Japanese eel herpesvirus HVA980811, marbled eel polyoma-like virus (MEPyV), aquabirnavirus MEIPNV1310 and aquareovirus CSV. By contrast, MECF-1 was noted refractory to megalocytiviruses RSIV-Ku and GSIV-K1 infection. Moreover, the cells were resistant to betanodavirus infection. In conclusion, MECF-1 derived from marbled eel is suitable for studies on anguillid viruses and interaction with host cells.

Optimization of the Conical Angle Design in Conical Implant–Abutment Connections: A Pilot Study Based on the Finite Element Method

Conical implant–abutment connections are popular for their excellent connection stability, which is attributable to frictional resistance in the connection. However, conical angles, the inherent design parameter of conical connections, exert opposing effects on 2 influencing factors of the connection stability: frictional resistance and abutment rigidity. This pilot study employed an optimization approach through the finite element method to obtain an optimal conical angle for the highest connection stability in an Ankylos-based conical connection system. A nonlinear 3-dimensional finite element parametric model was developed according to the geometry of the Ankylos system (conical half angle = 5.7°) by using the ANSYS 11.0 software. Optimization algorithms were conducted to obtain the optimal conical half angle and achieve the minimal value of maximum von Mises stress in the abutment, which represents the highest connection stability. The optimal conical half angle obtained was 10.1°. Compared with the original design (5.7°), the optimal design demonstrated an increased rigidity of abutment (36.4%) and implant (25.5%), a decreased microgap at the implant–abutment interface (62.3%), a decreased contact pressure (37.9%) with a more uniform stress distribution in the connection, and a decreased stress in the cortical bone (4.5%). In conclusion, the methodology of design optimization to determine the optimal conical angle of the Ankylos-based system is feasible. Because of the heterogeneity of different systems, more studies should be conducted to define the optimal conical angle in various conical connection designs.

An unusual cause of food-induced anaphylaxis in mothers

BACKGROUND

Galacto-oligosaccharides (GOS) are prebiotics added to commercial milk formula of infants and mothers. In recent years, cases of allergy related to GOS in atopic children have been reported in the South East Asian region.

CASE PRESENTATIONS

We describe a series of pregnant (n = 4) and lactating mothers (n = 2) who developed anaphylactic reactions after consumption of maternal milk formula containing GOS. All six subjects had pre-existing atopy and a positive skin prick test to GOS and 5/5 of the subjects who were tested had positive basophil activation tests to GOS. All of the mothers and their babies had normal neonatal outcomes after the reactions.

CONCLUSIONS

The supplementation of GOS into milk and beverages in the Asian region should take into account the rare chance of allergenicity of GOS in the atopic population.

Stress distribution of the patellofemoral joint in the anatomic V-shape and curved dome-shape femoral component: a comparison of resurfaced and unresurfaced patellae

PURPOSE

Whether to resurface the patella in knee replacement remains a controversial issue. The geometrical design of the trochlear groove in the femoral component could play an important role in determining the stress distribution on the patellofemoral joint, but this has not been sufficiently reported on. This study attempted to determine the effect of implant design on contact mechanics by means of a finite element method.

METHODS

Two designs, an anatomical V-shape design (VSD) and a dome-shape design (DSD), for the anterior trochlear surface in a contemporary femoral component were chosen for examining the contact characteristics. The use and absence of patella resurfacing was simulated. The stress and strain distribution on the patellar bone and the polyethylene component were calculated for comparison.

RESULTS

Without patellar resurfacing, the maximal compressive strain in the patellar bone in the VSD model was about 20 % lower than the DSD model. On the other hand, with resurfacing, the maximal strain for the VSD model was 13.3 % greater than for DSD. Uneven stress distribution at the bone-implant interface was also noted for the two designs.

CONCLUSION

The femoral component with a V-shape trochlear groove reduced the compressive strain on the unresurfaced patella. If resurfacing the patella, the femoral component with a curved domed-shape design might reduce the strain in the remaining patellar bone. Uneven stress could occur at the bone-implant interface, so design modifications for improving fixation strength and medialization of the patellar button would be helpful in reducing the risk of peg fracture or loosening.

LEVEL OF EVIDENCE

III.

Change in collateral ligament length and tibiofemoral movement following joint line variation in TKA

PURPOSE

The primary intent of total knee arthroplasty is the restoration of normal knee kinematics, with ligamentous constraint being a key influential factor. Displacement of the joint line may lead to alterations in ligament attachment sites relative to knee flexion axis and variance of ligamentous constraints on tibiofemoral movement. This study aimed to investigate collaterals strains and tibiofemoral kinematics with different joint line levels.

METHODS

A previously validated knee model was employed to analyse the change in length of the collateral ligaments and tibiofemoral motion during knee flexion. The models shifted the joint line by 3 and 5 mm both proximally and distally from the anatomical level. The data were captured from full extension to flexion 135°.

RESULTS

The elevated joint line revealed a relative increase in distance between ligament attachments for both collateral ligaments in comparison with the anatomical model. Also, tibiofemoral movement decreased with an elevation in the joint line. Conversely, lowering the joint line led to a significant decrease in distance between ligament attachments, but greater tibiofemoral motion.

CONCLUSION

Elevation of the joint line would strengthen the capacity of collateral ligaments for knee motion constraint, whereas a distally shifted joint line might have the advantage of improving tibiofemoral movement by slackening the collaterals. It implies that surgeons can appropriately change the joint line position in accordance with patient's requirement or collateral tensions. A lowered joint line level may improve knee kinematics, whereas joint line elevation could be useful to maintain knee stability.

LEVEL OF EVIDENCE

V.

The potential role of strontium ranelate in treating particle-induced osteolysis

Ultra high molecular weight polyethylene (UHMWPE) wear-particle-induced osteolysis is one of the major issues affecting the long-term survival of total joint prostheses. Currently, there are no effective therapeutic options to prevent osteolysis from occurring. The aim of this study was to evaluate the role of strontium ranelate (SR) in reducing the risk of particle-induced osteolysis. Forty-eight C57BL/6J ultra-high molecular weight polyethylene (UHMWPE) particle-induced murine calvarial osteolysis models were used. The mice were randomized into four groups as: sham (Group 1), UHMWPE particles (Group 2), and SR with UHMWPE particles (Group 3 and Group 4). Groups 1 to 3 were sacrificed at two weeks and group 4 was sacrificed at the fourth week. The skulls were then analyzed with a high-resolution micro-CT. Histological evaluation was then conducted and osteoclast numbers were analyzed for comparison. Based on the micro-CT, percentage bone volume and trabecular thickness were found to be significantly higher in Group 4 than in Group 2 (p<0.001). Osteoclast numbers in SR treated groups (Group 3 and Group 4) were reduced when compared to groups that did not receive SR treatment (Group 2). These results indicated that SR treatment helps to increase bone volume percentage and trabecular thickness and also suppresses osteoclast proliferation. It is suggested that oral SR treatment could serve as an alternative therapy for preventing particle-induced osteolysis.

In vivo biological response to highly cross-linked and vitamin e-doped polyethylene--a particle-Induced osteolysis animal study

Polyethylene particle-induced osteolysis is the primary limitation in the long-term success of total joint replacement with conventional ultra high molecular weight polyethylene (UHMWPE). Highly cross-linked polyethylene (HXLPE) and vitamin E-doped cross-linked polyethylene (VE-HXLPE) have been developed to increase the wear resistance of joint surfaces. However, very few studies have reported on the incidence of particle-induced osteolysis for these novel materials. The aim of this study was to use a particle-induced osteolysis animal model to compare the in vivo biological response to different polymer particles. Three commercially available polymers (UHMWPE, HXLPE, and VE-HXLPE) were compared. Osseous properties including the bone volume relative to the tissue volume (BV/TV), trabecular thickness (Tb. Th), and bone mineral density (BMD) were examined using micro computed tomography. Histological analysis was used to observe tissue inflammation in each group. This study demonstrated that the osseous properties and noticeable inflammatory reactions were obviously decreased in the HXLPE group. When compared with the sham group, a decrease of 12.7% was found in BV/TV, 9.6% in BMD and 8.3% in Tb.Th for the HXLPE group. The heightened inflammatory response in the HXLPE group could be due to its smaller size and greater amount of implanted particles. Vitamin E diffused in vivo may not affect the inflammatory and osteolytic responses in this model. The morphological size and total cumulative amount of implanted particles could be critical factors in determining the biological response.

Derivation of exemption formulas for air quality regulatory applications

The regulatory agencies and the industries have the responsibility for assessing the environmental impact from the release of air pollutants, and for protecting environment and public health. The simple exemption formula is often used as a criterion for the purpose of screening air pollutants. That is, the exemption formula is used for air quality review and to determine whether a facility applying for and described in a new, modified, or revised air quality plan is exempted from further air quality review. The Bureau of Ocean Energy Management's (BOEM) air quality regulations are used to regulate air emissions and air pollutants released from the oil and gas facilities in the Gulf of Mexico. If a facility is not exempt after completing the air quality review, a refined air quality modeling will be required to regulate the air pollutants. However, at present, the scientific basis for BOEM's exemption formula is not available to the author. Therefore, the purpose of this paper is to provide the theoretical framework and justification for the use of BOEM's exemption formula. In this paper, several exemption formulas have been derived from the Gaussian and non-Gaussian dispersion models; the Gaussian dispersion model is a special case of non-Gaussian dispersion model. The dispersion parameters obtained from the tracer experiments in the Gulf of Mexico are used in the dispersion models. In this paper, the dispersion parameters used in the dispersion models are also derived from the Monin-Obukhov similarity theory. In particular, it has been shown that the total amount of emissions from the facility for each air pollutant calculated using BOEM's exemption formula is conservative.

IMPLICATIONS

The operation of offshore oil and gas facilities under BOEM's jurisdiction is required to comply with the BOEM's regulations. BOEM's air quality regulations are used to regulate air emissions and air pollutants released from the oil and gas facilities in the Gulf of Mexico. The exemption formulas have been used by BOEM and other regulatory agencies as a screening tool to regulate air emissions emitted from the oil and gas and other industries. Because of the BOEM's regulatory responsibility, it is important to establish the scientific basis and provide the justification for the exemption formulas. The methodology developed here could also be adopted and used by other regulatory agencies.

Predicting 3D pose in partially overlapped X-ray images of knee prostheses using model-based Roentgen stereophotogrammetric analysis (RSA)

After total knee replacement, the model-based Roentgen stereophotogrammetric analysis (RSA) technique has been used to monitor the status of prosthetic wear, misalignment, and even failure. However, the overlap of the prosthetic outlines inevitably increases errors in the estimation of prosthetic poses due to the limited amount of available outlines. In the literature, quite a few studies have investigated the problems induced by the overlapped outlines, and manual adjustment is still the mainstream. This study proposes two methods to automate the image processing of overlapped outlines prior to the pose registration of prosthetic models. The outline-separated method defines the intersected points and segments the overlapped outlines. The feature-recognized method uses the point and line features of the remaining outlines to initiate registration. Overlap percentage is defined as the ratio of overlapped to non-overlapped outlines. The simulated images with five overlapping percentages are used to evaluate the robustness and accuracy of the proposed methods. Compared with non-overlapped images, overlapped images reduce the number of outlines available for model-based RSA calculation. The maximum and root mean square errors for a prosthetic outline are 0.35 and 0.04 mm, respectively. The mean translation and rotation errors are 0.11 mm and 0.18°, respectively. The errors of the model-based RSA results are increased when the overlap percentage is beyond about 9%. In conclusion, both outline-separated and feature-recognized methods can be seamlessly integrated to automate the calculation of rough registration. This can significantly increase the clinical practicability of the model-based RSA technique.

A 3D mathematical model to predict spinal joint and hip joint force for trans-tibial amputees with different SACH foot pylon adjustments

A solid-ankle cushioned heel (SACH) foot is a non-joint foot without natural ankle function. Trans-tibial amputees may occur toe scuffing in the late swing phase due to a lack of active dorsiflexion. To address this problem, clinical guidelines suggests shortening the pylon to produce a smooth gait. However, this causes a leg length discrepancy, induces asymmetry in the hip joint, and causes an overload of L5/S1 joint force. Therefore, this study aimed to investigate the influence of different prosthesis pylons on the hip joint and L5/S1 joint forces. Ten subjects were recruited using leg length for normalisation. Four different pylon reductions (0%, 1%, 2%, and 3%) were used for gait analysis. A Vicon system and force plates were used to collect kinematic data and ground reaction force, respectively. The software package MATLAB was used to create a mathematical model for evaluating the symmetry and force of the hip joint and the low back force of the L5/S1 joint. The model was validated by the correlation coefficient (CC=0.947) and root mean square (RMS=0.028 BW). The model estimated that the 1% group had a symmetrical hip joint force and a lower L5/S1 joint force in the vertical direction. This study indicates that a 1% pylon shortening on a SACH prosthesis is appropriate for a trans-tibial amputee.

Clinical results of hamstring autografts in anterior cruciate ligament reconstruction: a comparison of femoral knot/press-fit fixation and interference screw fixation

PURPOSE

To compare the clinical outcomes of femoral knot/press-fit anterior cruciate ligament (ACL) reconstruction with conventional techniques using femoral interference screws.

METHODS

Among patients who underwent arthroscopic ACL reconstruction with hamstring autografts, 73 were treated with either a femoral knot/press-fit technique (40 patients, group A) or femoral interference screw fixation (33 patients, group B). The clinical results of the 2 groups were retrospectively compared. The inclusion criteria were primary ACL reconstruction in active patients. The exclusion criteria were fractures, multiligamentous injuries, patients undergoing revision, or patients with contralateral ACL-deficient knees. In the femoral knot/press-fit technique, semitendinosus and gracilis tendons were prepared as 2 loops with knots. After passage through a bottleneck femoral tunnel, the grafts were fixed with a press-fit method (grafts' knots were stuck in the bottleneck of the femoral tunnel). A tie with Mersilene tape (Ethicon, Somerville, NJ) over a bone bridge for each tendon loop and an additional bioabsorbable interference screw were used for tibial fixation.

RESULTS

The mean follow-up period was 38 months (range, 24 to 61 months). A significant improvement in knee function and symptoms was reported in most patients, as shown by improved Tegner scores, Lysholm knee scores, and International Knee Documentation Committee assessments (P < .01). The results of instrumented laxity testing, thigh muscle assessment, and radiologic assessment were clearly improved when compared with the preoperative status (P < .01). No statistically significant difference in outcomes could be observed between group A and group B (P = not significant).

CONCLUSIONS

In this nonrandomized study, femoral knot/press-fit ACL reconstruction did not appear to provide increased anterior instability compared with that of conventional femoral interference screw ACL reconstruction. Favorable outcomes with regard to knee stability and patient satisfaction were achieved in most of our ACL-reconstructed patients using femoral knot/press-fit fixation with hamstring tendon autograft.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Biomechanical comparison of the K-ROD and Dynesys dynamic spinal fixator systems - a finite element analysis

Dynamic spinal fixators, such as the Dynesys (DY) and K-ROD (KD) systems, are designed to restore spinal stability and to provide flexibility. The long-term complications of implant breakage and the biomechanics of the adjacent and the bridged levels using the KD system are still unknown. Therefore, this study aims to investigate and compare the biomechanical effects of the KD system and the DY system. Finite element (FE) models of the degenerated lumbar spine, the DY system, and the KD system were each reconstructed. Hybrid-controlled analysis was applied in the three FE models. The FE results indicated that the KD system supplies the most stiffness during extension and the least stiffness during flexion, in contrast to the DY system. In contrast to the DY system, the KD system increased the facet contact force of the adjacent level, but this system decreased the screw stress on the cranial adjacent disc and the pedicle during flexion.

Biomechanical analysis and design of a dynamic spinal fixator using topology optimization: a finite element analysis

Surgeons often use spinal fixators to manage spinal instability. Dynesys (DY) is a type of dynamic fixator that is designed to restore spinal stability and to provide flexibility. The aim of this study was to design a new spinal fixator using topology optimization [the topology design (TD) system]. Here, we constructed finite element (FE) models of degenerative disc disease, DY, and the TD system. A hybrid-controlled analysis was applied to each of the three FE models. The rod structure of the topology optimization was modelled at a 39 % reduced volume compared with the rigid rod. The TD system was similar to the DY system in terms of stiffness. In contrast, the TD system reduced the cranial adjacent disc stress and facet contact force at the adjacent level. The TD system also reduced pedicle screw stresses in flexion, extension, and lateral bending.

Decrease of hyperglycemia by syringaldehyde in diabetic rats

Syringaldehyde is one of the active principles from the stems of Hibiscus taiwanensis (Malvaceae) that has been mentioned to lower hyperglycemia. However, the potential mechanisms for this action of syringaldehyde remain obscure. In the present study, we used streptozotocin to induce diabetic rats (STZ-diabetic rats) as type 1-like diabetic rats and fed fructose-rich chow to rats as type 2-like diabetic rats. Then, we performed the postprandial glucose test and applied the hyperinsulinemic euglycemic clamp to investigate the actions of syringaldehyde. Also, the changes of gene expressions of enzyme relating to glucose homeostasis in muscle and liver were characterized. Syringaldehyde significantly decreased the postprandial plasma glucose in rats, while the plasma insulin was not modified by syringaldehyde. The glucose infusion rate (GIR) in fructose chow-fed rats using hyperinsulinemic euglycemic clamp was markedly improved by syringaldehyde. Additionally, repeated administration of syringaldehyde for 3 days in STZ-diabetic rats resulted in a marked reduction of phosphoenolpyruvate carboxykinase (PEPCK) expression in liver and an increased expression of glucose transporter subtype 4 (GLUT 4) in skeletal muscle. Our results suggest that syringaldehyde may increase glucose utilization to lower hyperglycemia in diabetic rats.

Thermal response of a dental tissue induced by femtosecond laser pulses

This paper reports a theoretical and experimental study for thermal transport in a thin slice of human tooth induced by a 120 fs, 800 nm pulse laser at a repetition rate of 1 kHz. The surface reflectivity of enamel and the convection heat transfer coefficient were determined using an inverse heat transfer analysis. Instead of a fully three-dimensional modeling, two simplified two-dimensional (2D) planar and axisymmetric heat conduction models were proposed to simulate the temperature fields. The temperature responses obtained from the 2D planar and axisymmetric model agree well with the experimental measurements. On the other hand, the one-dimensional (1D) result significantly differs from the 2D axisymmetric one, suggesting that care should be taken when a 1D thermal model is considered for estimating temperature response.

One-stage arthroscopic repair of rotator cuff tears with shoulder stiffness

PURPOSE

The purpose of this study is to describe a 1-stage treatment with concomitant arthroscopic capsular release and rotator cuff repair and present clinical outcomes with a minimum follow-up of 2 years.

METHODS

Arthroscopic rotator cuff repair was performed in 211 consecutive patients. Forty-three patients had severe concomitant shoulder stiffness at the time of the repair. In the stiffness group, 1-stage arthroscopic capsular release and rotator cuff repair were performed. Preoperative mean passive forward flexion was 124°, whereas external rotation at the side was 309°. All patients were evaluated at a minimum 2-year follow-up, which included a visual analog scale score for pain, tests of muscle power and range of motion, the Constant score, and the modified American Shoulder and Elbow Surgeons shoulder evaluation form and modified University of California, Los Angeles scores.

RESULTS

The mean visual analog scale score during motion at the last follow-up was 1.5 in the stiffness group and 1.3 in the non-stiffness group. In the stiffness group, forward flexion was 175° whereas external rotation at the side was 60° postoperatively; shoulder motion improved (P < .001) and was comparable with that of the contralateral side. Other functional outcome instruments showed no statistical difference between the 2 groups.

CONCLUSIONS

In this study, 1-stage treatment of patients with rotator cuff tears and shoulder stiffness was performed by arthroscopic capsular release and cuff repair, and overall satisfactory results were achieved in selected patients. The results of the stiffness group in this study were statistically the same as those in the non-stiffness group.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Effects of cord pretension and stiffness of the Dynesys system spacer on the biomechanics of spinal decompression- a finite element study

BACKGROUND

The Dynesys system provides stability for destabilized spines while preserving segmental motion. However, clinical studies have demonstrated that the Dynesys system does not prevent adjacent segment disease. Moreover, biomechanical studies have revealed that the stiffness of the Dynesys system is comparable to rigid fixation. Our previous studies showed that adjusting the cord pretension of the Dynesys system alleviates stress on the adjacent level during flexion. We also demonstrated that altering the stiffness of Dynesys system spacers can alleviate stress on the adjacent level during extension of the intact spine. In the present study, we hypothesized that omitting the cord preload and changing the stiffness of the Dynesys system spacers would abate stress shielding on adjacent spinal segments.

METHODS

Finite element models were developed for - intact spine (INT), facetectomy and laminectomy at L3-4 (DEC), intact spine with Dynesys system (IntDyWL), decompressed spine with Dynesys system (DecDyWL), decompressed spine with Dynesys system without cord preload (DecDyNL), and decompressed spine with Dynesys system assembled using spacers that were 0.8 times the standard diameter without cord pretension (DecDyNL0.8). These models were subjected to hybrid control for flexion, extension, axial rotation; and lateral bending.

RESULTS

The greatest decreases in range of motion (ROM) at the L3-4 level occurred for axial rotation and lateral bending in the IntDyWL model and for flexion and extension in the DecDyWL model. The greatest decreases in disc stress occurred for extension and lateral bending in the IntDyWL model and for flexion in the DecDyWL model. The greatest decreases in facet contact force occurred for extension and lateral bending in the DecDyNL model and for axial rotation in the DecDyWL model. The greatest increases in ROMs at L2-3 level occurred for flexion, axial rotation and lateral bending in IntDyWL model and for extension in the DecDyNL model. The greatest increases in disc stress occurred for flexion, axial rotation and lateral bending in the IntDyWL model and for extension in the DecDyNL model. The greatest increases in facet contact force occurred for extension and lateral bending in the DecDyNL model and for axial rotation in the IntDyWL model.

CONCLUSIONS

The results reveals that removing the Dynesys system cord pretension attenuates the ROMs, disc stress, and facet joint contact forces at adjacent levels during flexion and axial rotation. Removing cord pretension together with softening spacers abates stress shielding for adjacent segment during four different moments, and it provides enough security while not jeopardizes the stability of spine during axial rotation.

Failure of the rotating-hinge knee megaprosthesis

Recently, rotating hinge knee prostheses were applied more frequently due to improving modern implant designs. They are predominantly used in specific conditions with major bone defect or insufficiency of the collateral ligaments around the knee, often as salvage procedures. A case of rotating hinge knee megaprosthesis failure due to isolated tibial polyethylene stopper broken, which was never reported before, was investigated and treated in our institution. We suggested that rotating hinge knee prosthesis with incompetent medial collateral ligament is apt to failure due to the high valgus moment during gait. Sacrificing lateral collateral ligament or cutting the femur in slightly less than the normal 5° to 7° valgus may eliminate the risk of complication.